This invention relates to shock absorbing means for flow control devices, and more particularly to shock absorbing means for reciprocable flow control members of flow control devices such as valves.
Heretofore, such as shown in U.S. Pat. No. 3,433,250 dated Mar. 18, 1969, safety relief valves have been provided with means to absorb at least some of the impact forces upon reseating of a reciprocable valve member. However, upon reseating of the valve member, substantial radial deflection may occur after initial line contact of the valve sealing face with the fixed seat ring. Such radial deflection is undesirable and oftentimes results in undue wear and possible damage to the contacting faces.
Also, shock absorbing sealing means for flow control devices such as valves, have utilized elastomeric members for absorbing shock. For example, U.S. Pat. No. 4,858,642 dated Aug. 22, 1989 shows a pressure operated relief valve in which an elastomeric member is positioned between a valve disc and a disc holder to absorb shock forces upon reseating of the valve member resulting from a reduction in pressure after actuation of the valve member. Elastomeric members are subject to deterioration at high temperatures, such as temperatures over around 500 F for example.
Other impact type valves have utilized fluid metering for absorbing shock force upon impact of the valve member against a valve seat or for reducing the speed of movement of the valve member prior to impact thereby to minimize impact forces. Such fluid metering arrangements are costly, relatively complex, and do not usually absorb all of the impact forces.